User equipment and method

Abstract

Some techniques for preventing delay of updating a PDCP reception window in user equipment due to packet discarding are provided. One aspect of the present invention relates to user equipment comprising: a transmission and reception unit configured to transmit and receive a packet to/from a base station; a PDCP layer processing unit configured to determine for a PDCP (Packet Data Convergence Protocol) packet received from the base station whether a sequence number of the PDCP packet is within a reception window and perform a PDCP layer operation on the PDCP packet having the sequence number falling within the reception window; and a reception window updating determination unit configured to determine whether the packet received from the base station is a predefined updating trigger packet for causing the reception window to be updated and if the received packet is the updating trigger packet, cause the PDCP layer processing unit to update the reception window.

1 . User equipment comprising:
 a transmission and reception unit configured to transmit and receive a packet to/from a base station;   a PDCP layer processing unit configured to determine for a PDCP (Packet Data Convergence Protocol) packet received from the base station whether a sequence number of the PDCP packet is within a reception window and perform a PDCP layer operation on the PDCP packet having the sequence number falling within the reception window; and   a reception window updating determination unit configured to determine whether the packet received from the base station is a predefined updating trigger packet for causing the reception window to be updated and if the received packet is the updating trigger packet, cause the PDCP layer processing unit to update the reception window.   
     
     
         2 . The user equipment as claimed in  claim 1 , wherein the updating trigger packet is a PDCP packet having only a header part, and the reception window updating determination unit determines whether a size of the PDCP packet received from the base station is equal to a PDCP header size and if the size of the received PDCP packet is equal to the PDCP header size, causes the PDCP layer processing unit to update the reception window. 
     
     
         3 . The user equipment as claimed in  claim 1 , wherein the updating trigger packet is a PDCP data packet having a header part including a bit indicating that the PDCP data packet is the predefined updating trigger packet for causing the reception window to be updated, and the reception window updating determination unit determines whether the bit in the header part in the PDCP data packet received from the base station indicates that the PDCP data packet is the updating trigger packet and if the bit indicates that the PDCP data packet is the updating trigger packet, causes the PDCP layer processing unit to update the reception window. 
     
     
         4 . The user equipment as claimed in  claim 1 , wherein the updating trigger packet is a PDCP control packet including a value of an upper end or a lower end of the reception window to be configured by the PDCP layer processing unit, and upon detecting the value of the upper end or the lower end of the reception window to be configured by the PDCP layer processing unit in the PDCP control packet received from the base station, the reception window updating determination unit causes the PDCP layer processing unit to update the reception window with the detected value of the upper end or the lower end. 
     
     
         5 . The user equipment as claimed in  claim 1 , wherein the updating trigger packet is a PDCP control packet including discarding information regarding a PDCP packet discarded by the base station, and upon detecting the discarding information regarding the PDCP packet discarded by the base station in the PDCP control packet received from the base station, the reception window updating determination unit causes the PDCP layer processing unit to update the reception window based on the detected discarding information. 
     
     
         6 . The user equipment as claimed in  claim 1 , wherein the transmission and reception unit uses a Capability or transmits the updating trigger packet to indicate to the base station that the user equipment is capable of updating the reception window by the updating trigger packet. 
     
     
         7 . The user equipment as claimed in  claim 6 , wherein the transmission and reception unit indicates the Capability to the base station for each mode of a RLC (Radio Link Control) AM (Acknowledged Mode) and a RLC UM (Unacknowledged Mode). 
     
     
         8 . The user equipment as claimed in  claim 7 , wherein a bearer for the RLC UM has a reordering function in the PDCP layer. 
     
     
         9 . The user equipment as claimed in  claim 1 , wherein the updating trigger packet is a RRC (Radio Resource Control) message including a value of an upper end or a lower end of the reception window to be configured by the PDCP layer processing unit, and upon detecting the value of the upper end or the lower end of the reception window to be configured by the PDCP layer processing unit in a RRC message received from the base station, the reception window updating determination unit causes the PDCP layer processing unit to update the reception window with the detected value of the upper end or the lower end. 
     
     
         10 . The user equipment as claimed in  claim 1 , wherein the updating trigger packet is a RRC message including discarding information regarding a PDCP packet discarded by the base station, and upon detecting the discarding information regarding the PDCP packet discarded by the base station in a RRC message received from the base station, the reception window updating determination unit causes the PDCP layer processing unit to update the reception window based on the detected discarding information. 
     
     
         11 . A method for causing user equipment to update a reception window, wherein the user equipment determines for a PDCP (Packet Data Convergence Protocol) packet received from a base station whether a sequence number of the PDCP packet is within a reception window and performs a PDCP layer operation on the PDCP packet having the sequence number falling within the reception window, the method comprising:
 determining whether the packet received from the base station is a predefined updating trigger packet for causing the reception window to be updated; and   if the received packet is the updating trigger packet, updating the reception window.